搜索错误关键字“Cannot assign requested address”，"返回" JSON 内容，返回的引号是因为其实并不是远程接口返回的，而是 IdentityModel 返回的，毕竟直译后从字面意思理解“无法分配请求的地址”，也可以理解为不能正确发起请求，所以就是在发起请求的过程中产生的错误。

在和运维一起排查后得知被调用服务出现很多 close wait，导致连接数不能及时释放，连接数耗尽，所以就不能再建立新请求了。知道了原因接下来就好办了。顺藤摸瓜，找到发起请求的地方，将能 Close Dispose 的都处理了。

错误返回的完整内容如下：

{
	"AccessToken": null,
	"IdentityToken": null,
	"TokenType": null,
	"RefreshToken": null,
	"ErrorDescription": null,
	"ExpiresIn": 0,
	"Raw": null,
	"Json": null,
	"Exception": {
		"Message": "Cannot assign requested address",
		"Data": {},
		"InnerException": {
			"ClassName": "System.Net.Sockets.SocketException",
			"Message": "Cannot assign requested address",
			"Data": null,
			"InnerException": null,
			"HelpURL": null,
			"StackTraceString": "at System.Net.Http.ConnectHelper.ConnectAsync(String host, Int32 port, CancellationToken cancellationToken)",
			"RemoteStackTraceString": null,
			"RemoteStackIndex": 0,
			"ExceptionMethod": null,
			"HResult": -2147467259,
			"Source": "System.Private.CoreLib",
			"WatsonBuckets": null,
			"NativeErrorCode": 99
		},
		"StackTrace": "at System.Net.Http.ConnectHelper.ConnectAsync(String host, Int32 port, CancellationToken cancellationToken)\n   at System.Threading.Tasks.ValueTask`1.get_Result()\n   at System.Net.Http.HttpConnectionPool.CreateConnectionAsync(HttpRequestMessage request, CancellationToken cancellationToken)\n   at System.Threading.Tasks.ValueTask`1.get_Result()\n   at System.Net.Http.HttpConnectionPool.WaitForCreatedConnectionAsync(ValueTask`1 creationTask)\n   at System.Threading.Tasks.ValueTask`1.get_Result()\n   at System.Net.Http.HttpConnectionPool.SendWithRetryAsync(HttpRequestMessage request, Boolean doRequestAuth, CancellationToken cancellationToken)\n   at System.Net.Http.RedirectHandler.SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)\n   at System.Net.Http.HttpClient.FinishSendAsyncBuffered(Task`1 sendTask, HttpRequestMessage request, CancellationTokenSource cts, Boolean disposeCts)\n   at IdentityModel.Client.TokenClient.RequestAsync(IDictionary`2 form, CancellationToken cancellationToken)",
		"HelpLink": null,
		"Source": "System.Net.Http",
		"HResult": -2147467259
	},
	"IsError": true,
	"ErrorType": 3,
	"HttpStatusCode": 0,
	"HttpErrorReason": null,
	"Error": "Cannot assign requested address"
}

修改前源代码

/// <summary>
/// 统一获取 SpiderBIM token的通用方法
/// </summary>
/// <param name="config">配置信息</param>
/// <returns></returns>
public static TokenResponse GetAuthorizeAsync(SpiderBIMConfigOptions config)
{
    var tokenClient = new TokenClient(config.TokenUrl, config.ClientId, config.ClientSecret);
    var tokenResponse = tokenClient.RequestResourceOwnerPasswordAsync(config.Username, config.Password, config.Scope).GetAwaiter().GetResult();
    if (tokenResponse.IsError)
    {
        Console.WriteLine($"DEBUG {DateTime.Now:yyyy-MM-dd HH:mm:ss,fff} - ---------------------------- 获取 SPDToken 失败 ----------------------------{tokenResponse.ToJsonString()}");
        return null;
    }
    return tokenResponse;
}

修改后的代码

/// <summary>
/// 统一获取 SpiderBIM token的通用方法
/// </summary>
/// <param name="config">配置信息</param>
/// <returns></returns>
public static TokenResponse GetAuthorizeAsync(SpiderBIMConfigOptions config)
{
    using (var tokenClient = new TokenClient(config.TokenUrl, config.ClientId, config.ClientSecret))
    {
        var tokenResponse = tokenClient.RequestResourceOwnerPasswordAsync(config.Username, config.Password, config.Scope).GetAwaiter().GetResult();
        if (tokenResponse.IsError)
        {
            Console.WriteLine($"DEBUG {DateTime.Now:yyyy-MM-dd HH:mm:ss,fff} - ---------------------------- 获取 SPDToken 失败 ----------------------------{tokenResponse.ToJsonString()}");
            return null;
        }
        return tokenResponse;
    }
}

修改后的代码加上了 using 是的 tokenClient 在使用后及时被释放，避免被调用服务出现太多的 close wait。从而导致连接数被占用完。

所以就是因为没有注意到 tokenClient 是可以被 Dispose 的类，并且因为业务关系发起了频繁的请求，所以才导致问题的产生。